Git 2.0: git svn: Set default --prefix='origin/' if --prefix is not given

git-svn by default puts its Subversion-tracking refs directly in
refs/remotes/*. This runs counter to Git's convention of using
refs/remotes/$remote/* for storing remote-tracking branches.

Furthermore, combining git-svn with regular git remotes run the risk of
clobbering refs under refs/remotes (e.g. if you have a git remote
called "tags" with a "v1" branch, it will overlap with the git-svn's
tracking branch for the "v1" tag from Subversion.

Even though the git-svn refs stored in refs/remotes/* are not "proper"
remote-tracking branches (since they are not covered by a proper git
remote's refspec), they clearly represent a similar concept, and would
benefit from following the same convention.

For example, if git-svn tracks Subversion branch "foo" at
refs/remotes/foo, and you create a local branch refs/heads/foo to add
some commits to be pushed back to Subversion (using "git svn dcommit),
then it is clearly unhelpful of Git to throw

  warning: refname 'foo' is ambiguous.

every time you checkout, rebase, or otherwise interact with the branch.

The existing workaround for this is to supply the --prefix=quux/ to
git svn init/clone, so that git-svn's tracking branches end up in
refs/remotes/quux/* instead of refs/remotes/*. However, encouraging
users to specify --prefix to work around a design flaw in git-svn is
suboptimal, and not a long term solution to the problem. Instead,
git-svn should default to use a non-empty prefix that saves
unsuspecting users from the inconveniences described above.

This patch will only affect newly created git-svn setups, as the
--prefix option only applies to git svn init (and git svn clone).
Existing git-svn setups will continue with their existing (lack of)
prefix. Also, if anyone somehow prefers git-svn's old layout, they
can recreate that by explicitly passing an empty prefix (--prefix "")
on the git svn init/clone command line.

The patch changes the default value for --prefix from "" to "origin/",
updates the git-svn manual page, and fixes the fallout in the git-svn
testcases.

(Note that this patch might be easier to review using the --word-diff
and --word-diff-regex=. diff options.)

[ew: squashed description of <= 1.9 behavior into manpage]

Suggested-by: Thomas Ferris Nicolaisen <tfnico@gmail.com>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Eric Wong <normalperson@yhbt.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/t/t9114-git-svn-dcommit-merge.sh b/t/t9114-git-svn-dcommit-merge.sh
index d33d714006..fb41876677 100755
--- a/t/t9114-git-svn-dcommit-merge.sh
+++ b/t/t9114-git-svn-dcommit-merge.sh
@@ -48,7 +48,7 @@ test_expect_success 'setup svn repository' '
 test_expect_success 'setup git mirror and merge' '
 	git svn init "$svnrepo" -t tags -T trunk -b branches &&
 	git svn fetch &&
-	git checkout -b svn remotes/trunk &&
+	git checkout -b svn remotes/origin/trunk &&
 	git checkout -b merge &&
 	echo new file > new_file &&
 	git add new_file &&
@@ -81,7 +81,7 @@ test_debug 'gitk --all & sleep 1'
 
 test_expect_success 'verify post-merge ancestry' "
 	test x\`git rev-parse --verify refs/heads/svn\` = \
-	     x\`git rev-parse --verify refs/remotes/trunk \` &&
+	     x\`git rev-parse --verify refs/remotes/origin/trunk \` &&
 	test x\`git rev-parse --verify refs/heads/svn^2\` = \
 	     x\`git rev-parse --verify refs/heads/merge\` &&
 	git cat-file commit refs/heads/svn^ | grep '^friend$'